On March 24 the bridgehead, the city and the castle were attacked by Jerzy Sebastian Lubomirski, with a Polish corps of 6,000 men. In the castle there were large stores of ammunition that Swedes the needed. The castle was held by Colonel Cronlood, with barely 280 men. However, Swedish garrison managed to flee down the river San in boats, saving most of the provisions, while the main army's artillery shelled the Poles. However, 4,000 grenades were left with matches lit, so the castle was blown in the air, together with several hundred Poles.[2]
In the evening 300 Swedish soldiers departed from the Swedish camp, and in three boats crossed the San River. The troops immediately removed the Polish guards and more Swedish troops crossed the river, including cavalry who swam over with their horses. Lithuanians who held this river bank believed the entire Swedish army was on them, and fled in panic.
On March 26, Swedish army built a bridge over the River San, and the entire army crossed over. They took the abandoned camp left by the Lithuanians, and got a rest of a night. On April 5, they were in security inside Warsaw's walls.[3]